In this paper, we propose a model that combines a Landau free energy part and a micromagnetic free energy part aimed at describing a magnetostructural multiferroic. We show that in the limit of high-elastic anisotropy and strong magnetostructural interplay, the model is able to reproduce characteristic strain and magnetization configurations typical of magnetic shapememory materials. For low-elastic anisotropy, in the presence of disorder arising from compositional fluctuations giving rise to a distribution of local transition temperatures, the model is able to reproduce strain glass behaviour. In this case, the temperature dependence of the magnetization measured after zero magnetic field cooling deviates from the magnetization measured after magnetic field cooling protocol, which proves that the strain glass behaviour induces non-ergodicity in the magnetic degrees of freedom as well. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim